JPH10233038A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute sufficient printing always stably with a thermal transfer printer and to obtain sufficient resolution by incorporating a compd. which has a solubility parameter in a specific range, does not contribute to UV curing and does not react with the other components in an ink compsn. into a UV curing compsn. to be used for a printing layer. SOLUTION: A recording layer, a metallic reflection layer, a protective layer and the printing layer are laminated on a transparent substrate. The printing layer cures the ink compsn. consisting essentially of a UV curing resin. The compd. which has a solubility parameter within a range of 7 to 10, does not contribute to UV curing and does not react with the other components in the ink compsn. is incorporated into the ink compsn. of such optical recording medium. The compd. is preferably at least one kind among paraffin, acrylate oligomer and oil and fat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to an optical recording medium whose surface can be written with a writing instrument or a thermal transfer printer.

[0002]

2. Description of the Related Art At present, compact disks (hereinafter abbreviated as CDs), laser disks (hereinafter abbreviated as LDs), digital video disks (hereinafter abbreviated as D) are widely used.
For a read-only optical recording medium such as VD), a substrate having information is manufactured by an injection molding method based on a master usually called a stamper. According to this method, a medium having the same information can be produced inexpensively and in large quantities, but it is not suitable for producing a small amount of a medium because the stamper is very expensive. Further, with the progress of the information society in recent years, there has been a growing demand for higher density recording than magnetic recording media.
Therefore, an optical recording medium for producing a small amount of an information recording medium or allowing a user to freely record and store data has been developed.

[0003] Optical recording media are classified into two types: a write-once type in which information can be recorded and reproduced, and a rewritable type in which data can be erased after recording. Among them, a single-recordable write-once compact disc is called a CD-R, which is a normal read-only CD.
Users are gradually increasing because of compatibility with. After purchasing a medium without data, the CD-R must allow the user to know in some way what information is recorded on the medium in order to write the data.

Recently, DVDs compatible with DVDs have been developed.
A write-once optical recording medium called -R has also appeared, but also in this case, similarly to the CD-R, it is necessary to know what information is recorded on the medium by some method.

[0005] Generally, a method of displaying a title or the like is a method of manually writing on the surface with an oil-based felt pen. However, when a medium is sold to an end user after data is inserted into a CD-R or the like. Handwriting is not preferred. On the other hand, the method of attaching a paper or film label such as a proppy disk has an advantage that a printer can print a well-designed character or picture. However, if it is desired to put characters on the entire surface of the disc, it is necessary to use a donut-shaped label having a large area, and it is very difficult to affix the label in alignment. In addition, when the label is coming off, there is a possibility that the label will come off in the apparatus and cause a trouble. Therefore, another method has been desired.

[0006]

Against the background of the above demands,
2. Description of the Related Art A method of displaying recorded contents and the like on a printing surface opposite to a light incident surface of a medium using a thermal transfer printer or the like has been put to practical use. When these are used, a user can freely display information on a disc based on a personal computer, but thermal transfer printing cannot be performed at all depending on the state of the printing surface, or even if thermal transfer printing can be performed, the resolution is very poor. There was a problem.

Japanese Patent Application Laid-Open Nos. 8-153341 and 8-1 disclose thermal transfer printing on an optical recording medium.
There is a description in 80642. However, JP-A-8-1
No. 53341 is a patent for an optical recording medium in which the recording characteristics are not deteriorated even by the heat of a thermal head by using a phthalocyanine dye or the like having good heat resistance for the recording layer. Is not described.

On the other hand, Japanese Patent Application Laid-Open No. 8-180642 discloses
It is a patent that refers to the print quality of thermal transfer printing on the label surface of the optical recording medium, which is provided with a fusion type thermal transfer image receiving layer on the label surface, using an inorganic porous layer for the image receiving layer,
Further, it has been proposed to improve the print quality by providing a soft resin layer below the inorganic porous layer. However, when used for an optical recording medium having a resin having a low glass transition temperature such as polycarbonate as a substrate, the substrate may be deformed by high-temperature drying for forming an inorganic porous layer, and the manufacturing process is complicated. There are problems such as becoming.

The present invention has been made to solve the above-mentioned drawbacks, and provides a recording medium having a surface corresponding to a thermal transfer type printer.
It is an object of the present invention to provide an optical recording medium capable of always performing a sufficient thermal transfer printing stably and obtaining a sufficient resolution.

[0010]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies, and as a result, have found that a UV curable ink composition containing a UV curable resin (hereinafter abbreviated as a UV curable resin) as a main component. Wherein the solubility parameter in the UV-curable ink composition is in the range of 7 to 10 and does not participate in ultraviolet curing (hereinafter abbreviated as UV curing), and other components in the ink composition Incorporation of a compound that does not react, desirably having a solubility parameter of 7 to 10
By containing at least one substance of paraffin, acrylate oligomer, oil and fat in the range of
The inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention

(1) At least a recording layer, a metal reflective layer, a protective layer, and a printing layer are laminated on a transparent substrate, and the printing layer is obtained by curing an ink composition containing a UV-curable resin as a main component. An optical recording medium, characterized in that the ink composition contains a compound having a solubility parameter in the range of 7 to 10 and not participating in UV curing and not reacting with other components in the ink composition. Optical recording medium, and

(2) Compounds having a solubility parameter in the ink composition in the range of 7 to 10 and not participating in UV curing and not reacting with other components in the ink composition include paraffin, acrylate oligomer, The optical recording medium according to (1), wherein the optical recording medium is at least one kind of fat or oil.

(3) The printing layer is characterized by covering the whole or a part of the protective layer (1) or (2).
And (4) a solubility parameter of 7 to 10 contained in the print layer.
Wherein the UV curable ink composition contains 0.01 to 5% by weight of a compound which is not involved in UV curing and does not react with other components in the ink composition. (1) The optical recording medium according to any one of (1) to (3),

(5) The optical recording medium according to any one of (1) to (4), wherein the surface of the printing layer is printed by a thermal transfer printer.

(6) UV-curable monomers,
In a UV curable ink composition containing an oligomer, a polymerization initiator and a filler for coloring and / or matting,
The solubility parameter is in the range of 7-10 and UV
A UV-curable ink composition comprising a compound that does not participate in curing and does not react with other components in the ink composition.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The solubility parameter in the present invention is generally abbreviated as SP, and is a numerical value for characterizing the solubility of resins, polymers, solvents and the like.
It is given by the square root of the cohesive energy density of the material.
If the chemical structure of a substance is known, it can be easily calculated from the molecular binding constant. It can also be measured experimentally by comparing the degree of dissolution and swelling with a substance whose solubility parameter is known. It is known that when several kinds of resins, polymers, and the like are mixed, substances having similar solubility parameter values have high compatibility and miscibility. The solubility parameter is a translation of the Solubility Parameter,
It is also called solubility parameter or solubility parameter. The solubility parameter is described in detail in "Flow of paint and dispersion of pigment" (TEMPLE. C. PATTON, Kyoritsu Shuppan Co., Ltd.), Chapter 13.

The optical recording medium used in the present invention is:
Although a transparent substrate, a recording layer, a metal reflective layer, a protective layer, and a printing layer are laminated from below, a base layer or an intermediate layer may be laminated in order to improve the characteristics. Further, a plurality of protective tanks may be laminated.

Since the substrate used in the present invention performs reproduction / recording by light, any material having high transparency can be used. Examples thereof include, but are not limited to, a polymer material such as a polycarbonate resin, an acrylic resin, a polystyrene resin, a vinyl chloride resin, an epoxy resin, a polyester resin, and a polyolefin, and an inorganic material such as glass. Among these, polycarbonate resin, acrylic resin, and polyolefin resin are desirable, and polycarbonate resin is more desirable, from the viewpoint of mechanical strength of the substrate, ease of providing grooves and read-only signals, and economic efficiency.

The shape of these substrates may be plate-like or film-like, and may be circular or card-like. Further, these substrate surfaces may have guide grooves and pits indicating recording positions, and pits for partially read-only information.
These grooves and pits are usually formed by a known method using a stamper.

The recording layer used in the present invention may use an inorganic material such as a silver alloy or a tellurium alloy, or may use an organic dye or polymer such as a cyanine, phthalocyanine, azo, porphyrin or pyromethene. However, those using an organic dye are generally used. These dyes may be substituted with various substituents for solubility in a solvent or recording characteristics. These dyes may be used alone or as a mixture of several types. Among these dyes, phthalocyanine dyes are particularly excellent in heat resistance and durability, and when a phthalocyanine dye is used in the recording layer, a good optical recording medium without deterioration of recording characteristics due to heat of a thermal head of a thermal transfer printer. Is obtained.

The recording layer containing the dye described above can be generally formed by a coating method such as spin coating, spray coating, or dip coating. When the dye is formed by a coating method, the dye may be dissolved and applied in a solvent that does not damage the resin substrate, that is, a solvent that does not substantially dissolve the resin for the substrate.

In the present invention, the thickness of the recording layer is usually 50 to 20.
0 nm is preferred. When forming a recording layer containing a dye, in addition to the above-described dye, resins such as nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, urethane resin, and the like, and a leveling agent, as long as the effects of the present invention are not impaired. A foaming agent and the like can be used in combination.

Although a recording layer mainly containing an organic dye is described, it is apparent that the present invention can be applied to a medium using an inorganic substance, a polymer, or a metal as the recording layer.

As the reflective layer provided on the recording layer in the present invention, a metal film having a high reflectivity such as gold, silver, aluminum, or an alloy thereof is used. These metal reflective layers can be formed by a method such as vapor deposition or sputtering. The thickness of these reflective layers is usually 500 to
About 2,000 angstroms is preferable. The reflective layer can be stacked in multiple layers.

A protective layer is provided on the above-mentioned reflective layer. Examples of the protective layer include those which polymerize by a general radical reaction such as acrylate or methacrylate, and those which perform cationic polymerization by light such as epoxy. . These resins may be polymerized singly or may be polymerized by mixing monomers and oligomers. It is also possible to dilute with a solvent and apply. Among them, it is desirable to use a UV-curable resin from the viewpoint of workability. When the protective layer is formed, spin coating, dip coating, bar coating, screen printing, or the like is performed. In many cases, the spin coating method is used because of good workability. These are used in a film thickness of 1 to 100 μm, preferably 1 to 20 μm. Not only one protective layer but also a protective layer may be laminated for the purpose of improving the scratch resistance, for example.

The printing layer may cover the entire protective layer thereunder or may cover only a part thereof. Printing is performed by a known printing method such as screen printing. U used for printing
V-curable ink composition is a monomer curable by UV,
It contains oligomers, polymerization initiators and colorants and / or fillers for matting. The color of the UV-curable ink composition is not particularly limited, and any color can be used as long as it is a commonly used UV-curable ink composition. Such a thing may be used. The UV-curable ink composition is not particularly limited as long as it contains a UV-curable resin as a main component, and may be a known UV-curable ink composition used for an optical recording medium.

Specific examples of the components of the UV curable ink composition include acrylate monomers such as ester acrylate monomers and epoxy acrylate monomers;
1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone are mixed with a resin in which acrylic oligomers such as ethylene glycol acrylate oligomer and urethane acrylate oligomer are mixed. And a thioxanthone-based polymerization initiator such as acetophenone-based and 2,4-diethylthioxanthone, and a coloring agent such as titanium oxide and a matting filler. The solubility parameter of the UV-curable ink composition is not particularly limited, but preferably about 8 to 12 is used.

A compound having a solubility parameter in the range of 7 to 10, which does not participate in UV curing, and which does not react with other components in the ink composition is added to the UV-curable ink composition. Paraffin having a solubility parameter in the range of 7 to 10 as the compound, not participating in UV curing, and not reacting with other components in the ink composition;
Desirably, it is at least one kind of acrylate oligomer and fat. More preferably, it is at least one substance of a paraffin, an acrylate oligomer, or a fat or oil that has a solubility parameter in the range of 7 to 9.5, does not participate in UV curing, and does not react with other components in the ink composition. Good. By including a compound satisfying this condition in the ink composition, sufficient thermal transfer printing was possible, and the resolution was significantly improved. The reason may be that the compound floats on the surface of the print layer obtained by UV-curing the ink composition and the surface state of the print layer changes.

Liquid paraffin is a specific example of paraffin, and 2-paraffin is a specific example of acrylate oligomer.
Ethylhexyl acrylate, an oligomer composed of 2-ethylhexyl methacrylate and butyl methacrylate (monomer ratio 1: 1), Resimix RL-4 (trade name, Mitsui Toatsu Chemicals, Inc.), etc. , Castor oil, linseed oil and the like.

When a compound having a solubility parameter of more than 10 is added, the surface state of a printing layer formed by a method such as screen printing becomes unsuitable for printing with a thermal transfer printer, and the resolution is deteriorated. On the other hand, if the solubility parameter is 7
When less than the compound is added, the UV-curable ink composition is liable to cause cloudiness and phase separation. For this reason, the deterioration of the stability of the ink and the deterioration of the printing state are easily caused.

The compound is preferably added in the range of 0.01 to 5% by weight, more preferably in the range of 0.02 to 3% by weight. If the addition amount is less than 0.01% by weight, the effect of addition is small, and if it exceeds 5% by weight, the viscosity is reduced, which is disadvantageous in terms of printability.

The compound has a solubility parameter of 7 to
Even if it is in the range of 10, if it reacts with other components in the ink, the compound will not float on the print layer surface,
The surface condition of the print layer does not change. A specific example of such a compound is silicone oil (methylphenylsiloxane). Silicone oils often have a solubility parameter in the range of 7 to 10, but cause a dealcoholization reaction with the hydroxyl group of the filler in the ink composition,
Since it is taken into the ink, it does not contribute to a change in the surface state of the print layer.

The applied UV-curable ink composition is cured by irradiation with UV light. When the composition is cured by irradiation with UV light, an energy of 150 to 2,000 mJ / cm ² is applied. Preferably it is 250 to 1,000 mJ / cm ² . This irradiation usually cures the coating in a matter of seconds.

As a UV lamp used for curing, a mercury lamp,
A high-pressure mercury lamp, an ultra-high-pressure mercury lamp or a metal halide lamp is desirable. By forming the print layer exposed on the surface in this way, it is possible to always perform a stable and sufficient thermal transfer printing with a thermal transfer printer.

The optical recording medium described in the present invention means a medium on which information can be recorded and / or reproduced by irradiating light, and is a medium on which information is already recorded. Alternatively, the medium may be an unrecorded medium on which information is to be recorded.

Japanese Patent Application Laid-Open Nos. 8-153341 and 8-18 disclose thermal transfer printing on an optical recording medium.
No. 0642 has already been described. However, JP-A-8-153341 is a patent for an optical recording medium in which the recording characteristics are not deteriorated even by the heat of a thermal head by using a phthalocyanine dye or the like having good heat resistance for the recording layer. The present invention is characterized in that sufficient resolution can be obtained even by printing with a thermal transfer printer by devising the printing layer, and the material used for the recording layer is not limited, so it is distinguished from the above patent. Is what is done.

Japanese Patent Application Laid-Open No. 8-180642 discloses an image receiving layer provided with a fusion type thermal transfer on the label surface.
The printing quality is improved by using an inorganic porous layer for the image receiving layer and further providing a soft resin layer below the inorganic porous layer.

On the other hand, according to the present invention, the UV
By adding a compound which has a solubility parameter in the range of 7 to 10 in the cured ink composition, does not participate in UV curing, and does not react with other components in the ink composition, only one printing layer can be used as a heat transfer type. The resolution of printer printing can be increased. Therefore, it is distinguished from the above technique.

[0039]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 An octane solution was used for a recording layer made of a phthalocyanine dye on an injection-molded polycarbonate resin substrate having a spiral groove (depth 140 nm, width 0.5 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 120 mm. The film was formed by spin coating. An Au thin film having a thickness of 100 nm was formed as a reflective layer on the recording layer by sputtering.
After spin-coating Dicure Clear SD-17 (trade name, Dainippon Ink and Chemicals, Incorporated: UV curable resin), UV was irradiated to form a 6 μm protective layer.

1% by weight of liquid paraffin (Kishida Chemical Co., Ltd.) having a solubility parameter of 8.6 was added to a UV curable white ink for CD (Dainichi Seika Kogyo Co., Ltd.), and the mixture was stirred and mixed. There was no turbidity or separation, and a good ink state was obtained for printing. The ink composition thus prepared was screen-printed and UV-coated on the protective layer.
Curing was carried out to form a printed layer, thereby obtaining a CD-R medium.
This printed layer had no stickiness on the surface, no streaks or unevenness, and a good printing state. When thermal transfer printing was performed on the printing surface with a thermal transfer printer (manufactured by Rimage), printing with very good resolution was achieved as shown in Table 1 [Table 1].

Example 2 The procedure was performed except that an acrylic oligomer (Resimix RL-4, Mitsui Toatsu Chemicals, Inc.) having a solubility parameter of 8.9 was added to the UV curable white ink for CD in an amount of 1% by weight. A CD-R medium was produced in the same manner as in Example 1. As shown in Table 1 [Table 1], good ink condition,
It was in a printing state. When thermal transfer printing was performed on the printing surface with a thermal transfer printer (RIMAGE), printing with very good resolution was achieved.

Example 3 CD-curable white ink for CD was prepared in the same manner as in Example 1 except that 1% by weight of coconut oil (Sankei Sangyo Co., Ltd.) having a solubility parameter of 8 was added. An R medium was prepared. As shown in Table 1 [Table 1], the ink state and printing state were good. When thermal transfer printing was performed on the printing surface with a thermal transfer printer (RIMAGE), printing with very good resolution was achieved.

Example 4 A UV curable matte ink for CD (Dainichi Seika Kogyo Co., Ltd.) having a solubility parameter of 8.
A CD-R medium was prepared in the same manner as in Example 1, except that 1% by weight of liquid paraffin (Kishida Chemical Co., Ltd.) was added. As shown in Table 1 [Table 1], the ink state and printing state were good. When thermal transfer printing was performed on the printing surface with a thermal transfer printer (RIMAGE), printing with very good resolution was achieved.

Comparative Example 1 A CD-R medium was produced in the same manner as in Example 1, except that no additive was added to the UV curable white ink for CD. As shown in Table 1 [Table 1], the ink state and the printing state were good, but the printing by the thermal transfer printer was blurred and it was difficult to read.

Comparative Example 2 A CD-R medium was produced in the same manner as in Example 1, except that 1% by weight of butylbenzyl phthalate having a solubility parameter of 11.0 was added to the UV curable white ink for CD. . As shown in Table 1 [Table 1], the ink state and the printing state were good, but the print was faint due to thermal transfer and was difficult to read.

Comparative Example 3 Silicone oil having a solubility parameter of 8 in UV curable white ink for CD (KF-
54 A Shin-Etsu Silicone Co., Ltd.) was added in the same manner as in Example 1 except that 1% by weight of the CD-R medium was prepared. Table 1
As shown in [Table 1], the ink state and the printing state were good, but the printing was faint due to thermal transfer, and it was difficult to read.

Comparative Example 4 A CD-R medium was produced in the same manner as in Example 4 except that no additive was added to the UV curable mat ink for CD. As shown in Table 1 [Table 1], the ink state and printing state were good, but printing with a thermal transfer printer was slightly difficult to read or faint.

[0048]

[Table 1] * 1 SP: solubility parameter * 2 BBP: butylbenzene phthalate

In Table 1, the ink state is a result of observing the occurrence of turbidity and separation when the ink is prepared and stored. In this case, it was evaluated as ×. The printing state is a result of observing the state of occurrence of streaks and unevenness of the printing layer and the state of stickiness of the surface. The thermal transfer resolution was evaluated as "O" when characters having a height of about 1/9 inch can be easily read without blurring when printed with a thermal transfer printer.

[0050]

According to the present invention, the UV curable ink composition used for the printing layer has a solubility parameter in the range of 7 to 10, does not participate in UV curing, and has other components in the ink composition. By containing a compound that does not react with
It is possible to provide an optical recording medium capable of always performing sufficient printing with a thermal transfer printer stably and obtaining sufficient resolution.

Continuing from the front page (72) Inventor Kenichi Arai 1900 Togo, Mogo-shi, Chiba Mitsui Chemicals Co., Ltd. (72) Inventor Yuichi Ito 1900 Togo, Togo, Mobara-shi, Chiba Mitsui Chemicals Co., Ltd. (72) Inventor Taisaku Kano 1900 Togo, Mobara City, Chiba Prefecture Mitsui Chemicals Co., Ltd. (72) Inventor Kawamoto Masayuki Kawamoto 10110, Clonton Ay, Clonton, Sukhumvit Road, Bangkok, Thailand Sukhumvit Street 43, Richmond Palace Condominium 26, 26/104

Claims (8)

[Claims] 1. A light obtained by laminating at least a recording layer, a metal reflective layer, a protective layer, and a printing layer on a transparent substrate, wherein the printing layer is obtained by curing an ink composition containing a UV-curable resin as a main component. In the recording medium, the ink composition contains a compound having a solubility parameter in a range of 7 to 10, and not participating in UV curing and not reacting with other components in the ink composition. Optical recording medium. 2. A compound having a solubility parameter in the range of 7 to 10 in the ink composition, which is not involved in UV curing, and which does not react with other components in the ink composition, is composed of paraffin, acrylate oligomer, oil or fat. At least one of
The optical recording medium according to claim 1, wherein the optical recording medium is a kind of substance. 3. The optical recording medium according to claim 1, wherein the printing layer covers the entire surface or a part of the protective layer. 4. A compound which has a solubility parameter in the range of 7 to 10 and is not involved in UV curing and does not react with other components in the ink composition.
The optical recording medium according to any one of claims 1 to 3, wherein the curable ink composition contains 0.01 to 5% by weight. 5. The optical recording medium according to claim 1, wherein printing is performed on the surface of the printing layer by a thermal transfer printer. 6. The optical recording medium according to claim 1, wherein the recording layer contains an organic dye. 7. The optical recording medium according to claim 1, wherein the recording layer contains a phthalocyanine dye. 8. A UV-curable ink composition containing a UV-curable monomer, oligomer, polymerization initiator and coloring and / or matting filler, wherein the solubility parameter is in the range of 7 to 10, and A UV-curable ink composition comprising a compound that does not participate in UV curing and does not react with other components in the ink composition.